椭圆通带
wp1=10;wp2=20;ws1=5;ws2=25;fs=100;rp=0.5;rs=50; wp1=10*2*pi;wp2=20*2*pi;ws1=5*2*pi;ws2=25*2*pi; wp=[wp1,wp2];ws=[ws1,ws2]; [n,wn]=ellipord(wp,ws,rp,rs,'s');
bw=wn(2)-wn(1);wo=sqrt(wn(1)*wn(2)); [z,p,k]=ellipap(n,rp,rs); [a,b,c,d]=zp2ss(z,p,k);
[a1,b1,c1,d1]=lp2bp(a,b,c,d,wo,bw); [num,den]=ss2tf(a1,b1,c1,d1);
[num1,den1]=impinvar(num,den,fs); [h2,w2]=freqz(num1,den1);
[num2,den2]=bilinear(num,den,fs); [h1,w1]=freqz(num2,den2); subplot(1,2,1);
plot(w2*fs/(2*pi),abs(h2)); subplot(1,2,2);
plot(w1*fs/(2*pi),abs(h1)); figure(1);
subplot(1,2,1);
zplane(num1,den1); subplot(1,2,2);
zplane(num2,den2);